A treatment method for removing a foreign body such as thrombus clogging a blood vessel involves use of an aspiration catheter having a long shaft formed therein with an aspiration lumen.
An aspiration catheter, in general, has a guidewire lumen in which a guidewire preceding in a living body is inserted and passed, and the aspiration catheter itself is inserted to a target part while being guided by the guidewire. Then, by a negative pressure generated by aspiration means such as a syringe connected to a hub provided at the proximal end of the aspiration catheter, the foreign body can be aspirated via an aspiration port at the distal end of the aspiration catheter into the aspiration lumen and be removed to the exterior.
For example, Japanese Patent Laid-open No. 2010-57831 discloses an aspiration catheter in which a guidewire lumen is integrally disposed on the distal side of an aspiration tube provided therein with an aspiration lumen, and the proximal end of the guidewire lumen is opened into the aspiration lumen. In addition, Japanese Patent Laid-open No. 2006-297063 discloses an aspiration catheter in which a guidewire tube is provided at an outer surface on the distal side of an aspiration tube.
Since an aspiration catheter as above-mentioned is inserted into a living body, its outside diameter should desirably be as small as possible. On the other hand, for assured aspiration of a foreign body, a sufficient flow path area (sectional area) of the aspiration lumen has to be secured. In addition, it is desirable for the aspiration catheter to be high in operationality (to possess good operational properties) such as a property of permitting easy and repeated removal of foreign bodies present at a plurality of parts in a living body, by one-time insertion of the aspiration catheter into the living body.
In the case of the aspiration catheter described in Japanese Patent Laid-open No. 2010-57831, however, the proximal end of the guidewire lumen opens into the aspiration lumen and, therefore, the guidewire has to be once pulled off at the time of aspiration. Therefore, at the time of moving the aspiration catheter distally and/or proximally in a living body for removing the next foreign body after removal of a foreign body, it is necessary to again insert the guidewire, leading to an intricate procedure. In the case of the aspiration catheter described in Japanese Patent Laid-open No. 2006-297063, the proximal opening portion of the guidewire lumen is partly embedded in a slant portion of an outer surface of the aspiration tube. Therefore, the proximal end of the guidewire inserted via the distal opening portion may be caught on the aspiration tube outer surface in the periphery of the proximal opening portion of the guidewire lumen, so that much labor may be needed to insert and pass the guidewire.